1961 Johnson 40hp Questions

[samo_ott]

I just picked up a RDSL23 40hp and as I'm used to 18 hp and smaller engines I have a few questions about it please. You can see it on the photo here: http://www.ovhi.ca/dsc06894.jpg

1) How does the compression relief work on the head? do I need to do anything or is it self sufficient.
2) I believe in the center of the pic there's the cutout switch? how does it work? Is it vacuum based?
3) 2 rubber hoses are cut and plugged (top and bottom). Should they be connected? The top one looks like it comes off the water jacket? Where should each go?

thanks for any answers... Steve

 

[jimmbo]

Re: 1961 Johnson 40hp Questions

1) the compression relief on your engine looks like the linkage to the recoil is missing.

2) the vaccumn cutout is connected the the intake manifold. It grounds out one cylinder when the throttle suddenly closed and then shifted into neutral.

3) The hose on the side of the cylinder should go around to the front of the engine and connect to the automatic choke heat exchanger. Another hose should leave the choke and come back to the bottom part of the block where the water is discharged into the exhaust housing

 

[F_R]

Re: 1961 Johnson 40hp Questions

To elaborate on #2, those motors have a nasty way of running away wild if you rev it up with no load, as in neutral or breaking a shear pin. When that happens, it won't slow back down. Scarey! The vacuum cut-out switch senses that condition and cuts out the spark to one cylinder till the RPMs come back down to normal.

#1, The valves in the head are supposed to be actuated by linkage to the recoil starter. When you pull the recoil, the valves are opened and the space inside the relief chambers (those "bumps" beside the valves) is added to the combustion chamber volume, thus lowering the pressure. Truth is, they only make it easier to pull the rope. If anything they are harder to get running with the compression relief working. That's why people take them off.

#3. You'll have to work the choke manually, since the automatic feature is disabled. They never did work worth a hoot anyway.

 

[jimmbo]

Re: 1961 Johnson 40hp Questions

My dads 1963 40hp had the same auto choke, it never gave us any trouble.

 

[F_R]

Re: 1961 Johnson 40hp Questions

Let me rephrase: MOST of them didn't work worth a hoot. Maybe climate has something to do with it too. Down here they would start up OK, but flood out from overchoking and you had to go back, open the door, and move the choke lever to manual off to keep it running.

 

[itstippy]

Re: 1961 Johnson 40hp Questions

Interesting pic. It looks like the head is an OEM replacement part (red), using the original head cover (white) and thermostat cover (also white). The starter recoil housing looks Evinrude blue and is probably not original which would explain the lack of relief valve linkage. As F_R states, the disconnected relief valve was a nothing anyway - they discontinued it completely in another year or so. The thermal choke being disconnected makes me suspect it (thermal choke)wasn't working properly on this motor. What's it look like starboard-side up front by the autochoke and carb?

 

[samo_ott]

Re: 1961 Johnson 40hp Questions

Thanks for the comments. I guess a lot of parts have been used over 45 years! So with no relief valve linkage the only difference is that it'll be hard to pull start? Not worried about that.

So should the hose to the choke (which is electric now, so I guess once it was water cooled then?) be connected to the drain at the base again or is that just a waste of cooling water

I just posted 5 photos of it here -> http://www.ovhi.ca/johnson40/johnson40_1.JPG (1 thru 5)

thx... Steve

 

[F_R]

Re: 1961 Johnson 40hp Questions

Yeah, it will just take more muscle to pull it. But not unreasonable. True, the recoil is from a later model and does not have the pulley for the compression relief arm, nor is it drilled and tapped for it.

As you suspect, the carb is also from something else. Could be from a 35hp, or a 28, or 33, or Gale 40 or ? Just leave the lines plugged, or completely remove the fittings and plug the holes for a cleaner look. It doesn't need the flow through there.